This invention concerns multi-well plates for organic chemical synthesis testing, and especially to multi-well plates useable in a microwave.
Organic chemical synthesis concerns the chemistry of the compounds of carbon and is fundamental to a broad range of industrial and research activities, notably pharmaceuticals, but also including polymer chemistry, the chemistry of food additives, flavor chemistry, as well as biochemistry.
Synthesis testing involves the determination of percentage yield of product from starting reagents. Synthesis testing may be performed in either the solid or liquid phases and is conveniently accomplished using a multi-well plate, wherein reagents of various concentrations in each well are permitted to react and form product compounds. The percentage yield for the various starting concentrations is measured and compared to determine the optimum reagent ratios which will yield the largest percentage of product.
When the reaction is endothermic or when heat is a catalyst, it is convenient to heat the reagents in a microwave oven. Microwave heating works by exciting molecules having a dipole moment at or near the resonant frequency of the dipole and, hence, is very selective in what is heated within the oven. For example, the microwaves bombarding a multi-well plate will heat the reagents within the wells but will not heat the plate or the air within the oven. While this is economical, because energy is not wasted heating items other than the constituents, there is a drawback in that temperature differences are present between items within the oven, such as between the reagents and the plate, as well as between the plate and the ambient air. Such temperature differences inevitably cause heat transfer to occur. For example, heat is transferred from the reagents to the plate and from the plate to the ambient air within the microwave chamber. The heat transfer leads to transient and static temperature gradients across the plate. Relatively lower temperatures are found in the wells near the edges of the plate where the heat transfer from the plate to the air is greatest due to the relatively large surface area of the side portions of the plate in contact with the air. Relatively higher temperatures are present in the wells near the center of the plate where the heat transfer is not as great because there is less surface area from which heat is lost.
The temperature gradients cause uneven results to occur, thereby biasing the testing and providing false results since all of the samples are not being tested at the same temperature due to the gradients formed across the plate. There is clearly a need for a multi-well plate useable in a microwave oven which does not suffer from the disadvantages of temperature gradients and which will yield consistent, uniform results in testing.
The invention concerns a multi-well plate for holding a compound for testing. The plate is formed from a substantially planar member having an upper surface and a plurality of side portions bounding the planar member. A plurality of wells are positioned in the planar member and are adapted to hold samples of the compound. Each of the wells has an opening located on the upper surface. A first group of the wells are arranged adjacent to one of the side portions. A first elongated body extends lengthwise along the one side portion adjacent to the first group of wells. The body has a capacity to act as a heat reservoir to resist temperature changes of the samples in the first group of wells relative to the samples in others of the wells. Preferably, the body extends substantially continuously around the planar member and serves as a heat reservoir to resist temperature changes of samples in any other adjacent wells.
In its preferred embodiment, the substantially planar member is bounded by downwardly depending side portions. The first group of wells is arranged adjacent to one of the side portions. The elongated body comprises a first elongated chamber which extends within the plate lengthwise along the one side portion and is positioned between the one side portion and the first group of wells. The first chamber is adapted to contain a fluid which has a capacity to act as a heat reservoir and resist temperature changes of the samples in the first group of wells relative to the samples in others of the wells.
In the preferred embodiment, the first chamber is filled with a liquid and is sealed to isolate it from the ambient. In an alternate embodiment, the chamber is initially air-filled and there is a port in the planar member in fluid communication with the first chamber. The port is adapted to receive the fluid, preferably a liquid which may be poured through the port to fill the first chamber. Preferably, the port is positioned on the upper surface.
The plate preferably has a second group of the wells arranged adjacent to another of the side portions and a second elongated chamber extending within the plate lengthwise along the other side portion. The second chamber is positioned between the other side portion and the second group of wells. Similar to the first chamber, the second chamber is also adapted to contain a fluid having a capacity to act as a heat reservoir and resist temperature changes of the samples in the second group of the wells relative to the samples in others of the wells. Preferably, the first and the second chambers are in fluid communication with each other.
In another embodiment, the elongated body is a solid material which may be heated by the microwaves and preferably extends continuously around the planar member. The solid material may be considered to form the side portions or it may be positioned within the elongated chamber.
It is an object of the invention to provide a multi-well plate suitable for use in a microwave oven.
It is another object of the invention to provide a multi-well plate in which temperature differences between wells is minimized.
It is another object of the invention to reduce or eliminate the presence of temperature gradients across the plate.
These and other objects of the invention will become apparent from consideration of the following drawings and detailed description of preferred embodiments of the invention.